RFE: Oscilloscope improvements

- [ ] I would like to have a toggle to view multiple channels at once in the waveform oscilloscope. Maybe channel 0 could be red, channel 1 could be yellow, and so on?
- [ ] I would like to have controls over the y-range of the oscilloscope. There could be a menu of options:
    * [-1, 1]
    * [0, 1]
    * Custom (some way of entering custom values)